How can I check whether my profile has been posted after registering?

If you ask the club directly, they should be able to tell you about your situation. I don’t think you can link your LINE account until your club registration is complete either.

After you register, they’ll send you your password and other details. Once you receive them, you can assume your profile has been posted. LINE integration? I believe it was fine even if you couldn’t set that up. That said, it seems processing can sometimes take a little over a week when they’re busy. If you still haven’t heard from them after 10 days following your interview, it might be worth contacting them.